Search results for query: *

Hi All, I am starting to commission a new chemical plant and have come across the following. Motor Volts - 3300v Motor FLA - 106A Motor Protection - Gemstart 4 Normally I would accept the Earth Fault Setting from betwwen 10% - 20% of FLA, in this case approximately 10 - 20A. We primary...

On a cable 'electrical characteristics' sheet what is meant by 'equivalent star reactance per 1000m of cable at 50Hz'. i.e. what is the star reactance. many thanks

In the standard for Inspection and maintenance of electrical installations in hazardous areas, what is meant by 'continuous supervision' and in what instance would it apply?

Could someone please explain the difference between 'Isochronous mode' and 'droop mode' when talking about two diesel generators connected in parallel on it's own common bus and not connected to a utility. Which method would be the best way to run these. many thanks

Hi, Could someone please explain the term 'field flashing' with reference to generators. What is it and how is it carried out. Many thanks in advance PaulUK

Hi All, What are typical values of fault levels for generators with respect to their ratings? Also could someone explain what is meant by saturated and unsaturated conditions. Many thanks in advance Paul

For installations below 1000v in the UK we use BS7671 16th edition as our standard for design and installation. Do we have an equivalent for installations above 1000v, that is, to what standards do we design our HV networks and Industrial distribution networks. Out of interest could people from...

Hi, Could I ask everyone what their interpretation is of an emergency stop in a motor control circuit. What makes it any emergency stop as apposed to a 'normal' stop function. I have seen stop buttons labelled up as emergency stop but all it does is drop the contactor out as does the normal...

Here in the UK when we calculate a cable size and type of protection to be used we take EFLI and Prospective Short Circuit Current (PSCC) readings at the source. Usually we measure back into the supply system which is back to a supply transformer through all associated cabling. The question is...

How would one decide on the correct choice of CT ratio for a protection CT? For example, If the normal current in the circuit was say 200A full load, would you select a primary rating of 200A or would some other factor come into play. Many thanks

Could someone please explain exactley what happens when a CT goes into saturation, e.g. does the secondary current drop off as the primary current still increase or does it flatten out, does it deviate from a sine wave. Thank you

Could someone please explain the difference between Balanced Earth Fault and Restricted Earth Fault. Many thanks in advance.

Hi, We are installing two new 4MVA transformers (11/3.3kv) to be connected in parallel to supply a switchboard feeding Motors. the 3.3kV switchboard will have a bus-section. The question is which transformer vector group should we use. Is there any preference to Yyn0 over Dyn11 etc. Could...